Marine multibeam sonar device

ABSTRACT

A marine multibeam sonar device comprises a processing element and a transmitter. The processing element generates a plurality of transmit transducer electronic signals and inverts a polarity of a first portion of the transmit transducer electronic signals. The transmitter is in communication with the processing element and includes a plurality of transmit electronic circuits and a plurality of transmit transducers. Each transmit electronic circuit receives and processes one of the transmit transducer electronic signals, wherein a first portion of the circuits re-inverts the polarity of the first portion of the transmit transducer electronic signals. The transmit transducers receive the processed transmit transducer electronic signals from the transmit electronic circuits and generate a sonar beam.

RELATED APPLICATIONS

The present application is a continuation of, and claims prioritybenefit to, co-pending and commonly assigned U.S. non-provisional patentapplication entitled “MARINE MULTIBEAM SONAR DEVICE,” application Ser.No. 14/604,335, filed Jan. 23, 2015, which claims the benefit under 35U.S.C. § 119(e) of provisional U.S. provisional patent applicationsentitled “MARINE SONAR DISPLAY DEVICE”, Application Ser. No. 62/024,833,filed Jul. 15, 2014; “MARINE MULTIBEAM SONAR DEVICE,” Application Ser.No. 62/024,843, filed Jul. 15, 2014; and “A SONAR TRANSDUCER ARRAYASSEMBLY AND METHODS OF MANUFACTURE THEREOF”, Application Ser. No.62/024,823, filed Jul. 15, 2014. These earlier-filed applications arehereby incorporated by reference into the current application in theirentirety.

BACKGROUND

Marine multibeam sound navigation and ranging (sonar) devices typicallyinclude one or more transmit devices to generate a sound beam into abody of water and one or more receive devices to detect the reflectionsof the sound beam. As a result of wave interference and through the useof beamforming techniques, the device may form a sonar beam whosedirection in the body of water can be controlled.

SUMMARY

Embodiments of the present technology provide a marine multibeam sonardevice that includes a sonar beam transmitter and receiver which eachutilize noise rejection techniques that involve inverting the polarityof various electronic signals communicated to the transmitter andreceiver. The marine multibeam sonar device comprises a receiver, amemory element, a processing element, and a transmitter. The receiverreceives receive reflections of a sonar beam and includes a plurality ofreceive channels and electronic circuitry. Each receive channel includesa receive transducer which generates a receive transducer electronicsignal with a polarity, wherein the polarity of a first portion of thereceive transducer electronic signals is inverted compared with thepolarity of the rest of the receive transducer electronic signals. Theelectronic circuitry receives the receive transducer electronic signalsand generates a receive signal including data from each of the receivetransducer electronic signals.

The processing element is in communication with the receiver and thememory element. The processing element receives the receive signal,re-inverts the polarity of the data from the first portion of thereceive transducer electronic signals, generates sonar data from thereceive transducer electronic signals, generates a plurality of transmittransducer electronic signals, and inverts a polarity of a first portionof the transmit transducer electronic signals.

The transmitter is in communication with the processing element andincludes a plurality of transmit electronic circuits and a plurality oftransmit transducers. Each transmit electronic circuit receives andprocesses one of the transmit transducer electronic signals, wherein afirst portion of the circuits re-inverts the polarity of the firstportion of the transmit transducer electronic signals. The transmittransducers receive the processed transmit transducer electronic signalsfrom the transmit electronic circuits and generate the sonar beam.

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the detaileddescription. This summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter. Other aspectsand advantages of the present technology will be apparent from thefollowing detailed description of the embodiments and the accompanyingdrawing figures.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

Embodiments of the present technology are described in detail below withreference to the attached drawing figures, wherein:

FIG. 1 is a perspective view of a marine multibeam sonar deviceconstructed in accordance with various embodiments of the currenttechnology;

FIG. 2 is block schematic diagram of electronic components of the marinemultibeam sonar device;

FIG. 3 is block schematic diagram of a plurality of transmit signalprocessing circuits and a plurality of transmit transducers;

FIG. 4 is a perspective view of a transmit beam generated by a transmittransducer array;

FIG. 5 is a rear view of the transmit beam and the transmit transducerarray;

FIG. 6 is block schematic diagram of a plurality of receive transducersand a receive signal processing circuit;

FIG. 7 is a perspective view of just the transmit transducer array and areceive transducer array, further illustrating the transmit beam and aplurality of receive beams;

FIG. 8 is a perspective view of the marine multibeam sonar device asonar beam;

FIG. 9 is a rear view of the marine multibeam sonar device and the sonarbeam; and

FIG. 10 is a flow diagram of at least a portion of the steps of a methodof generating an acoustic waveform with a transducer array including aplurality of transducers.

The drawing figures do not limit the present technology to the specificembodiments disclosed and described herein. The drawings are notnecessarily to scale, emphasis instead being placed upon clearlyillustrating the principles of the technology.

DETAILED DESCRIPTION

The following detailed description of the technology references theaccompanying drawings that illustrate specific embodiments in which thetechnology can be practiced. The embodiments are intended to describeaspects of the technology in sufficient detail to enable those skilledin the art to practice the technology. Other embodiments can be utilizedand changes can be made without departing from the scope of the presenttechnology. The following detailed description is, therefore, not to betaken in a limiting sense. The scope of the present technology isdefined only by the appended claims, along with the full scope ofequivalents to which such claims are entitled.

In this description, references to “one embodiment”, “an embodiment”, or“embodiments” mean that the feature or features being referred to areincluded in at least one embodiment of the technology. Separatereferences to “one embodiment”, “an embodiment”, or “embodiments” inthis description do not necessarily refer to the same embodiment and arealso not mutually exclusive unless so stated and/or except as will bereadily apparent to those skilled in the art from the description. Forexample, a feature, structure, act, etc. described in one embodiment mayalso be included in other embodiments, but is not necessarily included.Thus, the present technology can include a variety of combinationsand/or integrations of the embodiments described herein.

Embodiments of the present technology relate to a marine multibeam sonardevice. The device includes a plurality of transmit channels to transmitsound waves into a body of water and a plurality of receive channels toreceive reflections of the sound waves. As a result of wave interferenceand through the use of beamforming techniques, the device may form asonar beam whose direction in the body of water can be controlled.Multibeam sonar devices traditionally have not been developed for theconsumer market. The devices are often large in size and may requiremultiple people to install them on a marine vessel. In addition, theperformance of traditional multibeam sonar devices may suffer as aresult of electrical noise from sources within the marine vessel.

Embodiments of the technology will now be described in more detail withreference to the drawing figures. Referring initially to FIGS. 1 and 2,a marine multibeam sonar device 10 is illustrated which may utilizebeamforming techniques on a plurality of transmit channels and aplurality of receive channels in order to produce a sonar beam whosedirection can be controlled. The marine multibeam sonar device 10 mayreduce size and cost by multiplexing signals from various channels andmay improve performance with noise rejection techniques that involveinverting the polarity of various electronic signals. The marinemultibeam sonar device 10 broadly comprises a transmitter 12, a receiver14, a housing 16, a memory element 18, and a processing element 20.

The transmitter 12 may include a plurality of transmit signal processingcircuits 22 and a plurality of associated transmit transducers 24. Thecombination of a transmit signal processing circuit 22 and itsassociated transmit transducer 24 forms a transmit channel. In anexemplary embodiment, the transmitter 12 may include twenty-fourtransmit channels. Each transmit signal processing circuit 22, as shownin FIG. 3, may process one of a plurality of transmit transducerelectronic signals, indicated as “TX” and “TX” in FIG. 3, and mayinclude a low pass filter 26, a variable gain amplifier 28, a poweramplifier 30, and a transformer 32.

The low pass filter 26 generally passes frequencies of one transmittransducer electronic signal that are below a cutoff frequency andattenuates frequencies that are greater than the cutoff frequency. Thelow pass filter 26 may also adjust a shape of the voltage waveform ofthe transmit transducer electronic signal. The low pass filter 26 mayinclude passive and active electronic components such as resistors,capacitors, operational amplifiers, and the like, to form filteringcircuits as are generally known. The cutoff frequency may be chosen tobe compatible with sonar operating frequencies.

The variable gain amplifier 28 generally amplifies one transmittransducer electronic signal with a gain that can be varied. Thevariable gain amplifier 28 may include passive and active electroniccomponents such as potentiometers, resistors, capacitors, operationalamplifiers, and the like, to form amplifying circuits as are generallyknown. The gain may be set by the processing element 20 according to ashading factor, as described in more detail below.

The power amplifier 30 generally amplifies one transmit transducerelectronic signal and may include passive and active electroniccomponents such as resistors, capacitors, operational amplifiers, linedrivers, and the like, to form amplifying circuits as are generallyknown. The power amplifier 30 may further convert the single-endedtransmit transducer electronic signal to a differential signal.

The transformer 32 generally changes the voltage of one transmittransducer electronic signal and may include a center tap transformerwith a primary and a secondary as is generally known. The primary mayreceive the differential signal from the power amplifier 30. The centertap of the secondary may be connected to ground, while a first terminalof the secondary may present a positive polarity of the transmittransducer electronic signal and a second terminal may present anegative polarity of the transmit transducer electronic signal. Inaddition, the transformer 32 may be configured as a step-up transformer,wherein the voltages of the secondary are greater than the voltage ofthe primary.

Each transmit signal processing circuit 22 receives one transmittransducer electronic signal from the processing element 20, filters it,amplifies it, and converts it to a double-ended signal with a positivepolarity and a negative polarity with respect to ground. In exemplaryembodiments, the device 10 may include twenty-four transmit transducersignals, twenty-four transmit signal processing circuits 22, andtwenty-four transmit transducers 24.

Each transmit transducer 24 may include a transducer formed frompiezoelectric materials like ceramics such as lead zirconate titanate(PZT) or polymers such as polyvinylidene difluoride (PVDF) that areconfigured to receive the transmit transducer electronic signal andproduce a series of mechanical vibrations or oscillations that generatesa corresponding sound beam. The sound beam may be produced with anacoustic polarity that corresponds to an electrical polarity of thetransmit transducer electronic signal. For example, a transmittransducer electronic signal with a positive electrical polarity maycause the transmit transducer 24 to generate a sound beam with positiveacoustic pressure, while a negative electrical polarity may result in asound beam with negative acoustic pressure. Thus, the transmittransducer 24 may have a polarity as indicated in FIG. 3.

The transmit transducers 24 may be coupled to the transformers 32 suchthat the transmit transducers 24 of the odd-numbered transmit channelsreceive the transmit transducer electronic signals with a first polaritywhile the even-numbered transmit channels receive the transmittransducer electronic signals with a second polarity that is opposite tothe first polarity. This coupling scheme may provide noise cancellationas discussed below. The transmit transducers 24 are typically positionedto form a linear array 34, as seen in FIGS. 1, 4, and 5, with spacingbetween adjacent transducers, wherein the spacing may be related to awavelength of the sound beam.

The components that form the transmit signal processing circuits 22 andthe transmit transducers 24 are typically placed on a printed circuitboard (PCB), on a flexible (flex) circuit, or combinations thereof. Inan exemplary embodiment, the components of the transmit signalprocessing circuits 22 are placed on a PCB, while the transmittransducers 24 are placed on a flex circuit.

The transmitter 12 may generate a transmit beam 36 based on the transmittransducer electronic signals, which are received from the processingelement 20. Each transmit transducer electronic signal is a series ofperiodic pulses, such as sine wave pulses or square wave pulses, whosephase can be adjusted. A single series of pulses may be referred to as a“ping”. Each transmit transducer 24 produces a sound beam upon receiptof the transmit transducer electronic signal. Given the close proximityof the transmit transducers 24 to one another in the transmit transducerarray 34, when each transmit transducer produces a sound beam,constructive and destructive wave interference may occur, creating apattern of nodes and antinodes that can be shaped to form the transmitbeam 36, which functions as a single sound beam.

The transmit beam 36 may include a main lobe and a plurality of sidelobes. The main lobe may receive most of the energy and may have ateardrop, or similar, shape that has a base which projects from thetransmit transducer array 34. The side lobes receive much less energyand project at angles that place them at the sides of the base of themain lobe. The side lobes may be attenuated by adjusting the gain of thevariable gain amplifier 28 of the transmit signal processing circuit 22connected to the appropriate transmit transducers 24. This gainadjustment may be known as “shading”, and the value of the gain may bethe shading factor. In some cases the gain for the variable gainamplifier 28 of the transmit signal processing circuit 22 connected tothe transmit transducers 24 near the center of the transmit transducerarray 34 may be adjusted to be greater than the gain for the transmittransducer 24 near the edges of the transmit transducer array 34.

In operation, the transmit beam 36 may be considered to have a roughlytriangular profile with a long, narrow base representing a swath wherethe beam impacts the water bed. The transmit beam 36 may be orientedsuch that its longitudinal axis is orthogonal to the axis formed by thetransmit transducer array 34. The direction of the transmit beam 36, orits angle α with respect to the array axis as seen in FIGS. 4 and 5, maybe controlled or formed by controlling the phase of each sound beam,which in turn may be controlled by the transmit transducer electronicsignals. Thus, by properly adjusting the phase of each transmittransducer electronic signal, the direction of the transmit beam 36 maybe varied. If the phases are adjusted on successive pings of thetransmit transducer electronic signals, then the transmit beam 36 may beswept through a range of angles. When the transmitter 12 is utilizedwith a marine vessel and the transmit beam 36 is swept, the beam may beswept from front to back of the vessel or from side to side, dependingon the orientation of the transmit transducer array 34. In addition, thewidth of the transmit beam 34, as shown in FIG. 4, may be controlled byadjusting the phase of each transmit transducer electronic signal.

When the marine multibeam sonar device 10 is operating in the marinevessel, electrical noise from sources such as the marine vessel engine,other electronic devices, or the marine multibeam sonar device 10 itselfmay affect the transmit transducer electronic signals. The noise may beintroduced anywhere along the transmit transducer electronic signal pathfrom the low pass filter 26 to the transmit transducer 24. This mayresult in each transmit transducer electronic signal including a datacomponent, which is supplied by the processing element 20, and a noisecomponent, which comes from the noise sources. One way to reduce theeffect that the noise has on the transmit beam 36 is to try to cancel itwhen forming the transmit beam 36 by taking advantage of destructivewave interference. Both the data component and the noise component havea polarity. Furthermore, both the data component and the noise componentare generated in the sound beam that is produced by each transmittransducer 24. If the polarity of the noise component of the sound beamproduced by each transmit transducer 24 is inverted as compared with thepolarity of the noise component of the sound beams from the two adjacenttransmit transducers 24, then the noise components may effectivelycancel one another due to destructive wave interference because half thenoise components have a positive polarity and the other half of thenoise components have a negative polarity. In an exemplaryimplementation, the noise components from the odd-numbered transmittransducers 24 may have a positive polarity, while the noise componentsfrom the even-numbered transmit transducers 24 may have a negativepolarity.

The polarity of the noise component of the sound beam from each transmittransducer 24 is determined by the polarity of the noise component ofthe transmit transducer electronic signal. Thus, inverting the polarityof the sound beam noise component involves inverting the polarity of theelectronic signal noise component, which means inverting the polarity ofthe transmit transducer electronic signal. This is accomplished as shownin FIG. 3 and discussed above wherein the double ended output of thetransformer 32 for the even-numbered transmit channels is reversedbefore it is connected to the transmit transducer 24. Therefore,inverting the polarity of the transmit transducer electronic signal asit goes to the transmit transducer 24 on every other channel may cancel,or at least greatly reduce, the electrical noise. In someconfigurations, other inversion configurations may be employed. Forinstance, pairs of channels may be inverted (two non-inverted channelsfollowed by two inverted channels), triplets may be inverted, and thelike.

However, inverting the polarity of the transmit transducer electronicsignal also inverts the polarity of the data component, which is whatgives the transmit beam 36 its proper shape. It would be undesirable toinvert the polarity of the data component of the transmit transducerelectronic signal for every other transmit channel. In order to avoidthis situation, the polarity of the data component of the transmittransducer electronic signal for the even-numbered transmit channels maybe generated in an inverted state by the processing element 20 beforethe transmit transducer electronic signal enters the data path shown inFIG. 3. The inverted polarity signals are indicated in FIG. 3 as “TX”.Thus, when the polarity of the transmit transducer electronic signal forthe even-numbered transmit channels is inverted by the transformers 32before being communicated to the transmit transducers 24, the polarityof the data component for the even-numbered transmit channels isactually re-inverted and restored to its proper state. As a result, thedata component of all of the transmit channels has the same polaritywhen the transmit beam 36 is generated by the transmit transducers 24.

In configurations, each of a first portion of the transmit transducers24, equivalent in number to the first portion of the transmit transducerelectronic signals, receives one of the re-inverted processed polaritytransmit transducer electronic signals. Thus, in some configurations,there may be an equal number of inverted and non-inverted channels.However, in other configurations, there may be a non-equal (odd) numberof inverted and non-inverted channels.

In exemplary embodiments, the polarity of the transmit transducerelectronic signals may be inverted on the PCB before the signal iscommunicated to the transmit transducers 24 on the flex circuit.However, the inversion of the polarity of the transmit transducerelectronic signals may be implemented in many other ways.

The receiver 14 may include a plurality of receive transducers 38 and areceive signal processing circuit 40, as seen in FIG. 6. Each receivetransducer 38 may also be considered as providing a receive channel. Inexemplary embodiments, the receiver 14 may include sixty receivetransducers 38 or sixty receive channels. The receive transducers 38 mayeach include a transducer formed from piezoelectric materials likeceramics such as lead zirconate titanate (PZT) or polymers such aspolyvinylidene difluoride (PVDF) that are configured to receive amechanical force or pressure. Each receive transducer 38 may generate areceive transducer electronic signal, which includes a variable voltagecorresponding to the mechanical force. As with the transmit transducer24, the receive transducer 38 may have a polarity, such as a positivesurface or terminal and a negative surface or terminal, wherein thepolarity of the voltage generated, and in turn, the receive transducerelectronic signal, may correspond to the polarity of the acousticpressure applied to the receive transducer 38. Typically, the receivetransducer electronic signal is a series of periodic pulses, such assine wave pulses. In some embodiments, the receive transducers 38 may beformed from the same material as the transmit transducers 24. In variousembodiments, the receive transducers 38 may be implemented such that thepolarity of the even-numbered receive transducer electronic signals isinverted compared with the polarity of the odd-numbered receivetransducer electronic signals. One way to invert the polarity of theeven-numbered receive transducer signals is to connect the positiveterminal of the even-numbered receive transducers 38 to ground and thenegative terminal to the receive signal processing circuit 40, while theodd-numbered receive transducers 38 have their negative terminalconnected to ground and their positive terminal connected to the receivesignal processing circuit 40.

The receive signal processing circuit 40 may include a plurality ofamplifiers 42, a multiplexer 44, a low noise amplifier 46, a variablegain amplifier 48, a low pass filter 50, an analog to digital converter(ADC) 52, a serializer 54, and a low voltage differential signal (LVDS)driver 56.

Each amplifier 42 generally receives one receive transducer electronicsignal from one receive transducer 38 and amplifies the signal. Eachamplifier 42 may include passive and active electronic components suchas resistors, capacitors, operational amplifiers, and the like, to formamplifying circuits as are generally known.

The multiplexer 44 generally performs a time division multiplexing ofthe receive transducer electronic signals from the amplifiers 42. Themultiplexer 44 may include a plurality of analog switches that receive aplurality of analog signals and selectively pass one of the signals. Themultiplexer 44 may include successive stages of analog switches. Themultiplexer 44 may further include a plurality of control signals thatselect the receive transducer electronic signal to pass to its output.The processing element 20 may control the level of the control signals.Typically, the control signals are set such that each receive transducerelectronic signal is passed to the output of the multiplexer 44 insuccessive order for consecutive time slots, each time slot lasting fora first period of time. Thus, the output of the multiplexer 44 may be areceive electronic signal which includes a stream of the receivetransducer electronic signals, each signal per time slot.

The low noise amplifier 46 generally amplifies the receive electronicsignal and may include passive and active electronic components such asresistors, capacitors, operational amplifiers, and the like, to formamplifying circuits as are generally known.

The variable gain amplifier 48 generally amplifies the receiveelectronic signal with a gain that can be varied. The variable gainamplifier 48 may include passive and active electronic components suchas potentiometers, resistors, capacitors, operational amplifiers, andthe like, to form amplifying circuits as are generally known.

The low pass filter 50 generally passes frequencies of the receiveelectronic signal that are below a cutoff frequency and attenuatesfrequencies that are greater than the cutoff frequency. The low passfilter 50 may include passive and active electronic components such asresistors, capacitors, operational amplifiers, and the like, to formfiltering circuits as are generally known. The low pass filter 50 mayalso perform an antialiasing function and thus, the cutoff frequency maybe related or proportional to the rate at which the ADC 52 samples thereceive electronic signal.

The ADC 52 generally samples the receive electronic signal and generatesa corresponding digital value. The analog to digital converter mayinclude comparators, encoders, and other passive and active componentsas are generally known. The ADC 52 may output a multibit, paralleldigital value corresponding to the voltage level of the receiveelectronic signal.

The serializer 54 generally receives the multibit, parallel digitalvalue of the receive electronic signal from the ADC 52 and converts itto a serial stream of bits. The serializer 54 may include shiftregisters or similar components that convert parallel data into serialdata.

The LVDS driver 56 generally converts the single ended serial bitstreamfrom the serializer 54 to a low voltage differential signal. The LVDSdriver 56 may include passive and active electronic components such asresistors, capacitors, operational amplifiers, and the like, to createdifferential signals. Furthermore, the LVDS driver 56 may output adifferential signal that conforms to the LVDS standard.

The receive signal processing circuit 40 may receive the receivetransducer electronic signals from the receive transducers 38 and maygenerate the receive electronic signal, which includes digital samplesof the receive transducer electronic signals in a differential voltagebitstream, indicated as RX 1-RX M in FIG. 6. The bitstream of digitalsamples forms a stream of packets, one packet for each receive channelin successive order, wherein the packet includes data from a time slicedportion of the associated receive transducer electronic signal. Thereceive signal processing circuit 40 may communicate the receive signalto the processing element 20.

In various embodiments, the low noise amplifier 46, the variable gainamplifier 48, the low pass filter 50, the ADC 52, the serializer 54, andthe LVDS driver 56 may implemented as one or more channels of an analogfront end circuit. Furthermore, the device 10 may include a plurality ofmultiplexers 44, wherein each multiplexer 44 multiplexes only a portionof the receive transducer electronic signals and communicates its outputto one of the channels of the analog front end circuit. In addition, theanalog front end circuit may generate a plurality of receive electronicsignals, each one including a bitstream of only a portion of the receivetransducer electronic signals.

The components that form the receive transducers 38 and the receivesignal processing circuits 40 are typically placed on a PCB, on a flexcircuit, or combinations thereof. In an exemplary embodiment, thereceive transducers 38 and the amplifiers 42 are placed on a flexcircuit, while the other components of the receive signal processingcircuit 40 are placed on a PCB. In various embodiments, the othercomponents of the receive signal processing circuit 40 are placed on thesame PCB as the transmit signal processing circuits 22.

The receive transducers 38 are typically positioned to form a lineararray 58, similar to the transmit transducer array 34 and seen in FIGS.1 and 7, with spacing between adjacent transducers, wherein the spacingmay be related to the wavelength of the transmit beam 36. Given theclose proximity of the receive transducers 38 to one another, thereflections of the transmit beam 36 received by the receive transducers38 may be subject to wave interference properties. In addition, the dataof each receive channel is associated with, or includes, a phase or timedelay which may be adjusted. These phase values may be utilized by theprocessing element 20 when sonar data is calculated, as described inmore detail below. A particular set of phase values may determine thereflections that are received at a particular angle with respect to thereceive transducer array 58. The combination of the particular phasevalues and receive channel data may be considered a receive beam 60, asseen in FIG. 7. Varying the phase values also varies the angle of thereceive beam 60, with one set of phase values for each angle desired.The receive beam 60 may have a roughly triangular profile with a long,narrow base representing a swath where the beam reflects from the waterbed. Furthermore, the receive beam 60 may be oriented such that itslongitudinal axis is orthogonal to the axis formed by the receivetransducer array 58.

The receive transducer array 58 may be oriented with its linear axisorthogonal to the linear axis of the transmit transducer array 34. Invarious embodiments, the receive transducer array 58 may be positionedsuch that one end of the receive transducer array 58 is adjacent to thecenter of the transmit transducer array 34, as seen in FIGS. 1 and 7.This orientation allows the receive beam 60 to be swept across the pathof the transmit beam 36 in order to determine the angular direction ofthe water bed features or other objects that reflect the transmit beam36.

The housing 16, as seen in FIGS. 1, 8, and 9, generally encloses theother components of the marine multibeam sonar device 10. The housing 16may include a top wall, a bottom wall, and four sidewalls. In someembodiments, the sidewalls may be rounded or may have a curvature. Thetransmit transducer array 34 and the receive transducer array 58 may bepositioned in an opening on the bottom wall, as seen in FIG. 1, so thatthey may be encapsulated and/or potted therein. In one configuration,the housing 16 is formed of molded plastic although other suitablematerials may be employed.

The housing 16 is typically mounted to a hull of the marine vessel, butmay be mounted anywhere which provides access to a body of water. Thespecific position and orientation of the housing 16 may depend on thetype of scanning for which the marine multibeam sonar device 10 isutilized. With down and side scanning, the housing 16 may be mounted tothe hull of the marine vessel such that the transmit transducer array 34and the receive transducer array 58 lie in a horizontal plane with thetransmit transducer array 34 extending between the forward and rear endsof the marine vessel and the receive transducer array 58 extendingbetween the port and starboard sides of the marine vessel. With forwardscanning, the housing 16 may be mounted to the hull of the marine vesselsuch that the transmit transducer array 34 and the receive transducerarray 58 lie in a plane that is tilted approximately 45 degrees, or anyother depression angle, with respect to the horizontal. In addition, thetransmit transducer array 34 may extend between the port and starboardsides of the marine vessel and the receive transducer array 58 mayextend between the forward and rear ends of the marine vessel. In someembodiments, the housing 16 may include one or more mechanisms, such asservo motors, that will tilt and rotate the transmit transducer array 34and the receive transducer array 58 in order to switch between modes ofscanning.

The memory element 18 may include data storage components such asread-only memory (ROM), programmable ROM, erasable programmable ROM,random-access memory (RAM) such as static RAM (SRAM) or dynamic RAM(DRAM), hard disks, floppy disks, optical disks, flash memory, thumbdrives, universal serial bus (USB) drives, or the like, or combinationsthereof. The memory element 18 may include, or may constitute, a“computer-readable medium”. The memory element 18 may store theinstructions, code, code segments, software, firmware, programs,applications, apps, services, daemons, or the like that are executed bythe processing element 20. The memory element 18 may also storesettings, data, documents, sound files, photographs, movies, images,databases, and the like.

The processing element 20 may include processors, microprocessors,microcontrollers, digital signal processors (DSPs), field-programmablegate arrays (FPGAs), analog and/or digital application-specificintegrated circuits (ASICs), or the like, or combinations thereof. Theprocessing element 20 may generally execute, process, or runinstructions, code, code segments, software, firmware, programs,applications, apps, processes, services, daemons, or the like, or maystep through states of a finite-state machine, or combinations of theseactions. The processing element 20 may be in communication with theother electronic components through serial or parallel links thatinclude address busses, data busses, control lines, and the like.

The processing element 20 may be configured to control the operation ofthe transmitter 12. The processing element 20 may generate the transmittransducer signal for each transmit transducer 24. Each transmittransducer signal may include a digital bitstream of ones and zeroesthat create a periodic waveform. The processing element 20 may generateeach transmit transducer signal so that it includes a bitstream with theproper phase adjustment of each transmit transducer 24 for thetransmitter 12 to project the transmit beam 36 at the desired angle α,as shown in FIGS. 4 and 5, and width, as shown in FIG. 4. In general,the processing element 20 may include pattern generating hardware orsoftware algorithms that can generate the bitstream. In addition, theprocessing element 20 may invert the polarity of the bitstream for everyother transmit channel. In exemplary embodiments, the processing element20 may invert the polarity of the bitstream for the even-numberedtransmit channels. In some configurations, the processing element 20 mayemploy other inversion schemes, such as inverting pairs of transmitchannels, inverting triplets of transmit channels, and the like.

In exemplary embodiments, a bitstream waveform pattern may be createdand stored in the memory element 18. The pattern may form a periodicwave, such as a sine wave, a triangle wave, a square wave, and the like.The pattern may be used to create a ping or a series of pings. Incertain embodiments, a plurality of bitstream waveform patterns may becreated and stored in the memory element 18, wherein each pattern mayform a different wave shape or have another unique characteristic.

When the transmit transducer array 34 is generating the transmit beam36, each transmit transducer 24 generates the same periodic acousticwaveform with the phase of the waveform appropriately adjusted to formthe transmit beam 36 and to steer it. Since the bitstream pattern ofeach transmit transducer electronic signal is used to create theacoustic waveform, the phase of each bitstream pattern is adjusted inorder to adjust the phase of the acoustic waveform emanating from thetransmit transducer 24. The processing element 20 communicates the samebitstream pattern to each transmit channel, but appropriately adjuststhe phase of the pattern for each channel. The processing element 20adjusts the phase of the bitstream pattern by selecting the appropriatebit within the pattern to start generating the bitstream. For example,if the bitstream pattern is 100 bits long, then the processing element20 may start generating the bitstream for a first transmit channel atbit 1 of the pattern, a second transmit channel at bit 20, a thirdtransmit channel at bit 30, and so forth, with all of the bitstreamsbeing generated and communicated to the transmitter 12 at roughly thesame time. Thus, the processing element 20 may generate the bitstreampattern for each transmit channel with an offset within the pattern.

Generally, the offset of the bitstream pattern for each transmit channelis determined by the position of the associated transmit transducer 24in the transmit transducer array 34. Some transmit channels may have thesame offset, while others may have a different offset. By offsetting thebitstream pattern for at least a portion of the transmit channels, theprocessing element 20 effectively sets the relative phase of eachtransmit transducer electronic signal and, in turn, the phase of theacoustic waveform generated by each transmit transducer 24. In thisfashion, the transmit beam 36 is properly formed. Furthermore, byadjusting the offset in the bitstream pattern for each transmit channel,the transmit beam 36 may be steered to the desired angle α. In addition,the processing element 20 may send a value to the variable gainamplifier 28 of each transmit signal processing circuit 22 to adjust itsgain in order to properly shade the side lobes of the transmit beam 36and/or adjust the width of the beam 36. The processing element 20 mayperform the above-described actions for each ping of the transmit beam36.

The processing element 20 may be configured to calculate sonar databased on the reception of the reflections of the transmit beam 36. Theprocessing element 20 may receive the receive transducer electronicsignals as a bitstream from the receive signal processing circuit 40.The bitstream may include a packet of data for the first receive channelfollowed by a packet of data for the second receive channel and so forthfor all of the receive channels.

As mentioned above for the transmit transducer electronic signals,electrical noise from a variety of sources may affect the receivetransducer electronic signals as well. Likewise, the receive transducerelectronic signals may each include a data component, supplied by thereceive transducer 38, and a noise component from the noise sources.Furthermore, the noise may be canceled, or at least greatly reduced, bytaking advantage of similar properties that the receive channels havewith the transmit channels. The noise components may be canceled byinverting their polarities on every other receive channel. The polarityof the noise component of the appropriate receive channels may beinverted by inverting the polarity of the appropriate receive transducerelectronic signals. Since the receive transducer electronic signals arereceived by the processing element 20 as a packet of data for eachreceive channel, the processing element 20 may invert the data includedin every other packet—thereby inverting the polarity of the noisecomponent for every other receive channel. In exemplary embodiments, theprocessing element 20 may invert the data from all of the even-numberedreceive channels. When the processing element 20 is calculating thesonar data as discussed in more detail below, the noise components maycancel each other out.

However, as with the transmit transducer electronic signals, invertingthe polarity of the receive transducer electronic signals also invertsthe polarity of the data component of those receive channels, whichwould cause a misinterpretation of the data from those channels. Inorder to avoid this problem, the polarity of the even-numbered receivetransducer electronic signals is inverted from the receive transducer38, as shown in FIG. 6 and discussed above. Thus, when the processingelement 20 inverts the data in the packets from the even-numberedreceive channels, the processing element 20 is actually re-inverting thedata so that the polarity of the receive transducer electronic signal isrestored to its proper state, thereby allowing the calculations of thesonar data to be performed correctly.

The processing element 20 may perform a series of calculations on thereceive channel data to determine the features of the water bed orunderwater objects in the path of the transmit beam 36. The processingelement 20 may set the phase value for each receive transducerelectronic signal to calculate sonar data for the receive beam 60 beingpositioned at a first angle. Typically, the first angle is set for thereceive beam 60 to point at one edge of the transmit beam 36 swath. Theprocessing element 20 may also adjust the phase value for each receivetransducer electronic signal to calculate sonar data for the receivebeam 60 being positioned at a plurality of incrementally increasingangles, wherein the last angle corresponds to the opposite edge of thetransmit beam 36 swath.

In some embodiments, the calculations of the sonar data may be performedas a set of simultaneous equations or a matrix equation. Furthermore,calculations such as a fast Fourier transform (FFT) may be performed tocompute the sonar data. The time delay from when the ping was generateduntil the reflections were received may determine the depth of objectsin the transmit beam 36 path or the water bed. The amplitude, intensity,or other characteristics of the sonar data may determine the density ofthe objects in the transmit beam 36 path or the water bed.

Referring to FIG. 7, the marine multibeam sonar device 10 may functionas follows. The transmitter 12 may receive the transmit transducerelectronic signals from the processing element 20 and, in turn, maygenerate a ping or a short burst of pings along the transmit beam 36path (whose angle is determined by controlling the phase of the transmittransducer electronic signal to each transmit transducer 24). Thereceive transducer array 58 may receive the reflections of the transmitbeam 36 and each receive transducer 38 may generate a receive transducerelectronic signal. The receive transducer electronic signals may becommunicated to the processing element 20, which performs a series ofcalculations on the data from each receive channel. The calculations maydetermine how the receive beams 60 are formed to receive the transmitbeam 36 reflections at successive angles. The combination of the singletransmit beam 36 and the multiple receive beams 60 may form a sonar beam62 where the transmit beam 36 and the receive beams 60 overlap. Thus,each sonar beam 62 may be thought of as emanating from a single pointand formed from a single transmit beam 36 and a plurality of receivebeams 60, as seen in FIG. 7, wherein the number of receive beams 60 maydepend on the resolution of the sonar beam 62 that is desired.Generally, the higher the number of receive beams 60, the greater theresolution. Furthermore, the sonar beam 62 may be projected at the sameangle α, as seen in FIGS. 8 and 9, with respect to the plane of thetransmit transducer array 34 and the receive transducer array 58 as thetransmit beam 36. In addition, since the sonar beam 62 is formed fromthe transmit beam 36, the width of the sonar beam 62, as shown in FIG.8, may be controlled by adjusting the phase of each transmit transducerelectronic signal.

The marine multibeam sonar device 10 may have one or more modes ofoperation. In a first mode, the marine multibeam sonar device 10 maygenerate the sonar beam 62 at a fixed angle α for repeated pings.Typically, the angle α is set for approximately 90 degrees, such thatthe sonar beam 62 points roughly straight down beneath the marine vesselfor down and side scanning or roughly straight forward for forwardscanning. This mode may be useful for surveying or mapping the waterbed. In addition, the sonar beam 62 may be set and held at angles αother than 90 degrees, depending on the application of the marinemultibeam sonar device 10. Furthermore, the width of the sonar beam 62may be adjusted so that more area of the water bed is covered when“live” sonar images are being viewed.

In a second mode, the sonar beam 62 may be swept across a range ofangles, wherein the sonar beam 62 is projected on a first ping at theminimum angle α. On successive pings, the sonar beam 62 may be projectedat incrementally increasing angles α until the maximum angle α isreached. When used for down and side scanning, the sonar beam 62 may beswept from forward to rear, or vice versa. When used for forwardscanning, the sonar beam 62 may be swept from starboard to port, or viceversa. This mode may be useful when the marine vessel is still or ismoving slowly, or when trying to locate underwater objects, such asschools of fish.

The marine multibeam sonar device 10 may be in communication withexternal equipment, devices, and systems that can display sonar imagerybased on the sonar data. Thus, the marine multibeam sonar device 10 maycommunicate the sonar data to the external equipment. Furthermore, theexternal equipment might direct the marine multibeam sonar device 10 asto the mode in which to operate. For example, depending on userpreferences, the external equipment might direct the marine multibeamsonar device 10 to hold the sonar beam 62 at a fixed angle or to sweepthe sonar beam 62.

At least a portion of the steps of a method 100, in accordance withvarious aspects of the current technology, of generating an acousticwaveform with a transducer array 34 including a plurality of transducers24 is listed in FIG. 10. The steps of the method 100 may be performed inthe order as shown in FIG. 10, or they may be performed in a differentorder. Furthermore, some steps may be performed concurrently as opposedto sequentially. In addition, some steps may not be performed.

Referring to step 101, an angle is determined at which the acousticwaveform is to be generated. The acoustic waveform may be a sonar beam62, or a portion thereof, generated by the transmit transducer array 34,which is implemented in a system or device for displaying sonar images,wherein each sonar image is derived from one or more pings of the sonarbeam 62. The angle of the sonar beam 62 may be determined by input fromthe user regarding viewing modes of the sonar images. For example, theuser may choose a viewing mode in which the sonar beam is generated at aconstant angle for repeated pings. Alternatively, the user may choose aviewing mode in which the sonar beam is swept across a range of anglesduring a series of pings.

Referring to step 102, a binary bitstream is formed from a binarybitstream pattern. The binary bitstream may be an arbitrary sequence ofones and zeros. The binary bitstream pattern may be a series of ones andzeros that corresponds to a shape of the acoustic waveform. The binarybitstream pattern may be periodic. When the binary bitstream istransmitted, as discussed below, exemplary embodiments of the binarybitstream include the specific binary bitstream pattern. The binarybitstream pattern may be stored in a memory element 18.

Referring to step 103, a phase may be determined for each of a pluralityof transmit transducer electronic signals. The transmit transducerelectronic signals are to be communicated to the transmit transducerarray 34, one signal to each transmit transducer 24. Each transmittransducer electronic signal is a periodic signal which includes thebinary bitstream and each signal has its own value of the phase. Thevalue may vary according to the angle at which the acoustic waveform isto be generated. The value may also vary according to the positionwithin the transmit transducer array 34 of the associated transducer 24.

Referring to step 104, an offset is determined within the binarybitstream pattern that corresponds to each determined phase. Since thebinary bitstream pattern is periodic, a phase of the pattern can bedetermined as well. The phase of the binary bitstream pattern may alsobe considered an offset, such as a bit position, within the bit pattern.Thus, the offset within the binary bitstream pattern corresponds to thephase of the transmit transducer electronic signal.

Referring to step 105, one transmit transducer electronic signal istransmitted to each of the transmit transducers 24. A processing element20 may transmit the transmit transducer electronic signals to thetransmit transducers 24. The transmit transducer electronic signals eachinclude a binary bitstream, and some embodiments of the processingelement 20 may include hardware and/or software to generate the binarybitstreams. However, exemplary embodiments of the processing element 20may retrieve the binary bitstream pattern from the memory element 18 andmay start generating the pattern at the offset point that corresponds tothe determined phase of the transmit transducer electronic signal foreach transducer 24.

Referring to step 106, each transmit transducer electronic signal isfiltered. The marine multibeam sonar device 10 may include transmitsignal processing circuits 22 that each include a low pass filter 26which may shape the waveform of the transmit transducer electronicsignal. The processing element 20 may transmit the transmit transducerelectronic signals to the transmit signal processing circuits 22 whichprocess the signals and then communicate them to the transmittransducers 24.

Although the technology has been described with reference to theembodiments illustrated in the attached drawing figures, it is notedthat equivalents may be employed and substitutions made herein withoutdeparting from the scope of the technology.

What is claimed is:
 1. A marine multibeam sonar device comprising: areceiver configured to receive reflections of a transmitted sonar beam,the receiver including— a plurality of receive channels, each receivechannel including a receive transducer configured to generate a receivetransducer electronic signal with a polarity, wherein the polarity of afirst portion of the receive transducer electronic signals is invertedcompared with the polarity of the rest of the receive transducerelectronic signals, and electronic circuitry configured to receive thereceive transducer electronic signals and generate a receive signalincluding data from each of the receive transducer electronic signals; amemory element; and a processing element in communication with thereceiver and the memory element, the processing element being configuredto— receive the receive signal, re-invert the polarity of the data fromonly the first portion of the receive transducer electronic signals suchthat the polarity of the data from the first portion of the receivetransducer electronic signals corresponds to the polarity of the rest ofthe receive transducer electronic signals, and generate sonar data fromthe re-inverted data from the first portion of the receive transducerelectronic signals and the data from the rest of the receive transducerelectronic signals.
 2. The marine multibeam sonar device of claim 1,wherein the receive signal further includes a stream of binary datapackets with each packet including data from a time sliced portion ofone of the receive transducer electronic signals, and the processingelement is further configured to deserialize the receive signal andretrieve the binary data packet for each receive channel contained inthe receive signal.
 3. The marine multibeam sonar device of claim 2,wherein the data from a first portion of the binary data packets,collected from the first portion of the receive transducer electronicsignals, has an inverted polarity compared with the polarity of the restof the binary data packets.
 4. The marine multibeam sonar device ofclaim 1, wherein each receive transducer includes a first terminal and asecond terminal and, for each of a first portion of the receivetransducers equivalent in number to the first portion of the receivetransducer electronic signals, the first terminal is connected toelectrical ground and the second terminal is connected to the electroniccircuitry of the receiver.
 5. The marine multibeam sonar device of claim4, wherein for the rest of the receive transducers, the first terminalis connected to the electronic circuitry of the receiver and the secondterminal is connected to electrical ground.
 6. The marine multibeamsonar device of claim 1, wherein the first portion of the receivetransducer electronic signals includes the receive transducer electronicsignals generated by even-numbered receive transducers.
 7. The marinemultibeam sonar device of claim 1, wherein each receive transducer has apositive polarity or a negative polarity, and wherein a first portion ofreceive transducers have an inverted polarity compared with the polarityof the rest of the receive transducers.
 8. The marine multibeam sonardevice of claim 7, the first portion of receive transducers having aninverted polarity correspond to receive channels for which the polarityof data for the first portion of the receive transducer electronicsignals is reinverted.
 9. The marine multibeam sonar device of claim 1,wherein the receive electronic circuitry comprises a multiplexerconfigured to perform time division multiplexing of the receivetransducer electronic signals.
 10. The marine multibeam sonar device ofclaim 9, wherein the multiplexer receives a receive transducerelectronic signal for each receive channel and outputs a stream of thereceive transducer electronic signals, each receive transducerelectronic signals allocated a time slot.
 11. A marine multibeam sonardevice comprising: a memory element; a receiver configured to receivereflections of a transmitted sonar beam, the receiver including aplurality of receive channels, each receive channel including a receivetransducer configured to generate a receive transducer electronic signalwith a polarity, wherein the polarity of a first portion of the receivetransducer electronic signals is inverted compared with the polarity ofa second portion of the receive transducer electronic signals; and aprocessing element in communication with the receiver and the memoryelement, the processing element being configured to— receive theplurality of receive transducer electronic signals and generate areceive signal having a stream of binary data packets with each packetincluding data from a time sliced portion of one of the receivetransducer electronic signals, re-invert the polarity of the data fromonly the first portion of the receive transducer electronic signals tocorrespond to the polarity of the data from the second portion of thereceive transducer electronic signals, and generate sonar data from there-inverted portion of the receive signal and the receive signalcorresponding to the second portion of the receive transducer electronicsignals.
 12. The marine multibeam sonar device of claim 11, wherein theprocessing element is further configured to deserialize the receivesignal and retrieve the binary data packet for each receive channelcontained in the receive signal.
 13. The marine multibeam sonar deviceof claim 11, wherein the data from a first portion of the binary datapackets collected from the first portion of the receive transducerelectronic signals has an inverted polarity compared with the polarityof the data from a second portion of the binary data packets collectedfrom the second portion of the receive transducer electronic signals.14. The marine multibeam sonar device of claim 11, wherein each receivetransducer includes a first terminal and a second terminal and, for eachof a first portion of the receive transducers equivalent in number tothe first portion of the receive transducer electronic signals, thefirst terminal is connected to electrical ground and the second terminalis connected to the electronic circuitry of the receiver, wherein forthe rest of the receive transducers, the first terminal is connected tothe electronic circuitry of the receiver and the second terminal isconnected to electrical ground.
 15. A marine multibeam sonar devicecomprising: a receiver configured to receive reflections of atransmitted sonar beam, the receiver including— a plurality of receivechannels, each receive channel including a receive transducer configuredto generate a receive transducer electronic signal with a polarity,wherein the polarity of a first portion of the receive transducerelectronic signals is inverted compared with the polarity of the rest ofthe receive transducer electronic signals, and electronic circuitryconfigured to receive the receive transducer electronic signals andgenerate a receive signal including data from each of the receivetransducer electronic signals; a memory element; and a processingelement in communication with the receiver and the memory element, theprocessing element being configured to— receive the receive signal,re-invert the polarity of the data for only a first portion of thereceive signal corresponding to the first portion of the receivetransducer electronic signals such that the polarity of the data fromthe first portion of the receive transducer electronic signalscorresponds to the polarity of the rest of the receive transducerelectronic signals, and generate sonar data from the receive signal. 16.The marine multibeam sonar device of claim 15, wherein the receivesignal includes a stream of binary data packets with each packetincluding data from a time sliced portion of one of the receivetransducer electronic signals, and the processing element is furtherconfigured to deserialize the receive signal and retrieve the binarydata packet for each receive channel contained in the receive signal.17. The marine multibeam sonar device of claim 16, wherein the data froma first portion of the binary data packets, collected from the firstportion of the receive transducer electronic signals, has an invertedpolarity compared with the polarity of the rest of the binary datapackets.